The invention relates to improvements in so-called electronic clutch managements (ECM) for use in motor vehicles. More particularly, the invention relates to improvements in systems for and methods of electronically managing automatically adjustable clutches in the power trains of motor vehicles. Still more particularly, the invention relates to a novel and improved system which can be utilized to manage or regulate the transmission of torque by an automatically adjustable clutch which is installed in a power train between a prime mover (such as a combustion engine) and a manually shiftable transmission of a motor vehicle. The invention also relates to a method of managing (i.e., of controlling the transmission of torque by) an automatically adjustable clutch (e.g., a friction clutch), particularly by resorting to the novel system.
It is already known to change the condition of an engageable, disengageable and partially engageable automatic clutch by a setting member which is displaceable under the command of a microcontroller. The arrangement is such that the clutch is disengaged without delay in response to actuation of a gear shift member (e.g., a lever) which is used by the operator of the motor vehicle to shift the transmission into a different gear, i.e., to change the ratio of the transmission. The microcontroller effects a reengagement of the clutch upon completion of shifting of the transmission into a different gear and the following synchronization of the transmission as soon as the microcontroller receives a signal denoting that the shifting of the transmission into a different gear is completed. A drawback of conventional electronic clutch management systems of the just outlined character is that, due to the mass inertia of the vehicle, the combustion engine can be "dragged" to increase its rotational speed (hereinafter called RPM for short) beyond a permissible limit during shifting of the transmission into a different gear, namely in response to shifting into too low a gear. Thus, there exists an urgent need for an effective protection of the engine against an increase (overrev) of its RPM beyond a still acceptable upper limit.
On the other hand, there can develop certain extreme driving circumstances, such as when the braking action is insufficient, when "dragging" of the engine to a high RPM might be desirable and advantageous in order to utilize the drag torque of the engine for the purpose of enhancing the braking action.